Ice sheets and glaciers were once more extensive than they are now, and covered much of the British Isles. By comparing landforms "then and now", it is possible to demonstrate quite easily what it took early geologists years to accept.

These 18th and early 19th century geologists, especially those who had never actually seen a glacier, found great difficulty in accepting that glaciers had once covered Britain. Some suggested that glacial striations were caused by carts or hob-nailed boots! Local Swiss villagers and geologists such as de Saussure in the mid 18th Century recognised that glaciers had formerly extended much further down their valleys, leaving evidence of erosion and deposition. James Hutton (the 'father of geology'), even though he hadn't visited Switzerland, realised that great granite blocks left 80 km from their alpine source were carried by ice and not (as was generally supposed at the time) by Noah's Flood.

In the mid 19th Century, another Swiss scientist, Louis Agassiz, campaigned vigorously in favour of his (and others') glaciation theory and applied the evidence to British examples in the face of stiff opposition, at least initially, from eminent geologists of the day, such as Lyell and Murchison.

Nowadays, we take it for granted that Britain was once covered by ice - but can you prove it?

Information about glacial erosion and glacial deposition is found in the relevant Study Guides.

• gives full images of the landforms shown below, and other glacial features, mainly from Britain;
• sets out to prove that they could only have been formed by glaciers;
• shows evidence that can be used to determine the maxiumum advance of glaciers and the direction in which they travelled;
• suggests how to answer exam questions on this topic.

Llanberis

Mickleden

Striding Edge

Glen Sannox

Grey Mare's Tail

Semer Water

Stirling

Whistling Sands

Kingsdale

The Then and Now Study Topic contains the following pages: